The last part of Pennsylvania’s Diesel-Powered Motor Vehicle Idling Act will take effect Saturday, taking away the temporary exemption allowing long-haul trucks to idle during mandated rest periods.

The exemption was included in the law to give operators time to install battery-operated heaters or small onboard generators, so that they would not rely on engine idling for cabin heat or cooling. All trucks and buses will now be limited to five minutes of idling in any hour, unless equipped with a new cleaner engine with a California sticker.

Signs and posters will go up along the Pennsylvania Turnpike and interstate highways reminding truck drivers of the state’s “No-Idle” law.

“We expect the No-Idle Law to improve air quality near truck stops and rest areas,” said Thomas Au, president of the Clean Air Board of Central Pennsylvania. “By restricting idling for trucks and buses, the law will reduce the public’s exposure to diesel emissions that can cause asthma, emphysema, and bronchitis.”

CAB helped enact the law in 2008, many of whose requirements became effective last year.